Minutes passed in post-coital bliss. Perhaps Mother checked first, before I thought to look beyond our more than comfortable tangle. Nell had disappeared.
Mom felt me move. "Keep it in me, Baby." She patted my head. I had been demoted, no longer Her Son. She was a mother telling her naughty boy how to behave.
I simply hummed, my need to dominate her was more than well satisfied. Our sloppy connection remained a source of delight. I teased her. "Going to stop taking the pill?"
She surprised me. "I don't, Craig, haven't for years."
"Huh?" Was she kidding me? "But I was sure-"
"Your father's sperm are not what they used to be. We would welcome another child."
"B-b-b-but-"
"Incest babies?" She used a mocking tone. "I'll take that risk to be a real mother again."
She had to be kidding! I nearly sputtered again and looked stupider than usual. So I dive-boarded off of stupid. "What if it's a girl who grows up like you and Nell? I'll want to spunk a baby in your granddaughter."
"As if I'd let you so much as breed your existing sister!" Mother scoffed, serious.
"Neither will she." I got on the serious bandwagon, to show I had been kidding, but I think an extra glob of my cum spat into Mom's cunt at the notion of impregnating one or both of my semi-slaves.
Nell came into the room eventually. "What is he, a dog? Can't get his knot out of your twat, Mom?"
We ignored her to the extent of not responding, but it was finally time to uncouple. "That was wonderful." I said sheepishly.
"All in good fun, Craig."
She and I used opposite ends of the throw to wipe our mess.
Nell rolled her eyes and flounced back to her room. "You owe me, Big Bro - 27 minutes plus some seconds." That's what she'd come out for.
To say I lost ten bucks but won the war would be accurate but inconsequential. All I cared about was, Nell had called me "Big Brother" in front of our mother.
"Is that some code?" Mom eyed me? "Not that I care anymore." She was dressing. "But I'm going to track Nelda's ovulation and decree blackout days."
"Sis will be eager to do that, and I'll be grateful." I said earnestly.
"And take care not to bruise her frequently, it's a cancer risk I hear."
I hadn't heard that, but I took the warning to heart. After dressing, Mother and I started dinner.
Dinner conversation was mild. It ended when Nell called me "Big Brother" again, after we had eaten. I stood up and told her to clear the table and clean everything, kitchen included. I invited Mom to play a video game while her daughter performed as instructed. Mom didn't so much as raise an eyebrow - about Nell, but she's not much of a gamer. She does enjoy first person exploration games with low violence.
When Nell appeared in the living room to tell us she was finished, I got up and took her to her bedroom. I wanted vengeance for losing our bet! "Goodnight, Mom."
Mom didn't have to remind me about my fertile sperm, but she did. "Don't-"
"Nell is on the pill." I reminded my concerned parent and followed my big-little sister.
"How many times did you nut today?" Nell sounded a little jealous, but she didn't want to be left in a lurch for a climax. She was holding her bedroom door open. She closed it behind us.
"Three, but here's your final test, Slave. I've spunked more often than that, in a day." I referred to the good-old-days of when I spanked it to ShirleyThreeCunt videos. Those were weak affairs. I would gladly trade their quantity for quality. Sex with Mom had been intense! Each time, I wondered if I could get it up again, but I put the onus on my randy sister. "What will you do to make sure my next nut fills your twat?"
"Whatever I have to." There was a hint frustration. Then she looked down, frowning. "Big Brother, what do you want?" Her change from defiance to submission tugged powerfully at my fantasy.
"I want you to finger yourself inside your panties. Watching you will keep me from being bored while I figure out how far to push you.
"All the way - short of bloodshed." She promised, reaching into her shorts.
"Ick." I took her at her word. I love my sister more than most siblings do, because we had the perfect balance of fight and fun. This was none of those. Nell expected me to feign complete lack of sympathy while having her obey and withstand my wishes until I didn't need her anymore.
I held all the cards as she masturbated in her pants and waited for my dick to get hard. Nell is smart though, smarter than me. She had a secret weapon. "Tell you what, Big Brother. I'll be your permanent slave."
Her eyes narrowed. If she was faking being serious, she was doing a great job of it. My dick was interested. "Don't say that unless you mean it."
"I've been considering this for a while." She pulled her hand out of her pants and licked her fingers. "It started when you and Mom convinced me to admit that I crave big dick - yours specifically because you're not just convenient, you're safe. I want to have your cock in me often, as often as you like - I totally confess it. The bigger reason is, I experienced something out of my world, when you destroyed my ass. It's still sore from days ago. There wasn't anything fun or good about it, but it was transcendent. There might be a drug alternative, but trusting you to respect our safe word is a wiser bet."
Whoa, that was a lot to hear. My big sister had reached a decision to surrender herself full-time to my sexual whims - because she, A: trusted me, B: craved my dick, and C: wanted to explore her masochistic domain.
My dick was rising faster than a thermometer inserted into an orifice. "I don't think you're faking, Nell, but maybe you're fooling yourself?" The presence of big cock, for her, was a clear bias to her thought train.
"Not much. I'm pretty sure." She saw what was happening in the crotch of my trousers and stepped closer. Her hands fiddled with the clasp. "What do you say, Big Bro? This cunt will be yours, if you just accept it."
"You're cock crazy." I challenged her with the extreme impression.
"I only get crazy when you're fucking me with this bad boy. She unzipped my trousers and reached into my boxers. Her hands felt warmer than usual. "Yeah, you'll nut before midnight."
"You know this is the worst time to be negotiating about enslaving yourself."